Author Topic: 1974 Formula 400 build (Read 1621 times)

JC455 · « **on:** May 07, 2018, 10:38:08 AM »

I posted this on PY Forums, but thought I'd copy it over here too.

JC455 · « **Reply #1 on:** May 07, 2018, 10:40:24 AM »

I’m going to attempt an on-going update of a very
S L O W build of my 74 Formula 400.
Updates may be sporadic... please bear with me... and my checkbook

JC455 · « **Reply #2 on:** May 07, 2018, 10:41:26 AM »

The inspiration for it all: My first car- 1976 Trans Am 455/4 speed. Built it from a POS to this beastie.... then sold it due to stupidity.

JC455 · « **Reply #3 on:** May 07, 2018, 10:44:11 AM »

The 74 back in 2014

My son inspecting it- lol

And posing next to it....

JC455 · « **Reply #4 on:** May 07, 2018, 10:46:03 AM »

It's a W66 Red/Red Formula 400/TH400 car.
It's lead a strange life- when I got it, there was no motor/trans, but it had SBC clam shell mounts on the frame... and a bunch of 'speed' parts stickers all over the radiator support.
I quickly dispatched the SBC stuff and started prepping it to receive some proper Pontiac power again.

« **Reply #4 on:** May 07, 2018, 10:46:03 AM »

JC455 · « **Reply #5 on:** May 07, 2018, 10:47:40 AM »

After some scrubbing w/ Simple Green...

JC455 · « **Reply #6 on:** May 07, 2018, 10:48:46 AM »

Cleaned up the crossmember

JC455 · « **Reply #7 on:** May 07, 2018, 10:50:10 AM »

Installed some new window seals...

JC455 · « **Reply #8 on:** May 07, 2018, 10:51:58 AM »

Started collecting some goodies for it...

JC455 · « **Reply #9 on:** May 07, 2018, 10:55:20 AM »

Everyone was going crazy for US Mags Bandit rims because they look so similar to Rally II rims, but I wanted something different, so I grabbed the Rambler rims in an 18" size.
This was necessary to clear the braking system that you'll see shortly.

Had to have the silly shot of my pup- he's a little over a year in this pic

Mocking up the 18x9.5 rear rim

The 18" size was necessary because of this:

and this in the rear:

JC455 · « **Reply #10 on:** May 07, 2018, 10:57:11 AM »

Many years ago, I was on NastyZ28.com and Pro-Touring.com and publicly commented on the similarity of the S10 and Corvette rear parking brake setup, and speculated that they could be used together as a hybrid. A gentleman who produces brake setups exchanged emails and PM's with me, and then he started marketing these:

Well, since I know what is involved in making it work, I just gathered my own parts to allow a staggered, C6 Z51 Corvette rear caliper disc brake setup. I just need to measure and cut some brackets to space the caliper upward from the S10 backing plate.

JC455 · « **Reply #11 on:** May 07, 2018, 11:40:56 AM »

I'm using CPP C5 spindles, but have upgraded to C7 Corvette wheel bearings and ARP hardware.
In this mock up, I was still using the cheap C5 bearing-- don't do this!

Many people have shared this M/C over the last decade- it seems to be a winner

This is it, along with a Tuff Stuff 9" dual diapraghm booster

and some Detroit Speed Low Angle brackets

JC455 · « **Reply #12 on:** May 07, 2018, 11:41:55 AM »

Then life kicked me in the arse...
Someone stole my dog, the well went dry, the house foundation developed a massive crack that lifted the south side of my two story home!
Long story short, had to move :-/
I'm finally getting back on it...

JC455 · « **Reply #13 on:** May 07, 2018, 11:43:21 AM »

So, here we are in 2018, and things are progressing... slowly....

My son getting down on the grinder

JC455 · « **Reply #14 on:** May 07, 2018, 11:45:33 AM »

The weather caused this

« **Reply #14 on:** May 07, 2018, 11:45:33 AM »

JC455 · « **Reply #15 on:** May 07, 2018, 11:48:38 AM »

I found a smoking deal on some C7 wheel bearings- these used to be considered race parts, and close to $500 each when they were on the C6 Vettes!
They are made by SKF, and average about $110 ea now that GM uses them on the C7's.

Comparison of the C5/C6 bearing(yellow studs) vs the C7 bearing(blue studs)

The fit in the spindle is SO much better with the AC Delco parts

JC455 · « **Reply #16 on:** May 07, 2018, 11:49:52 AM »

JC455 · « **Reply #17 on:** May 07, 2018, 11:52:41 AM »

275-40/18 vs 235-60/14 tire

14's-- note the large wheel well gap

18's- This is with it jacked up. The second pic is the driver's side resting on the ground... still a gap, but filled out better. This will look really good with some lowering springs in the rear.

ryeguy2006a · « **Reply #18 on:** May 07, 2018, 01:03:36 PM »

Wow, love this build! I would like to know more about that Z51 rear brake kit. I just picked up a complete set of Z51 rotors and calipers with brackets at a swap meet. I already swapped out the C5 rotors and calipers for the big Z51, but was looking to somehow adapt the rear Z51's to the rear LS1 brakes I currently have.

roadking77 · « **Reply #19 on:** May 07, 2018, 01:24:29 PM »

Looking forward to this one. I'm glad your son has gotten his hands dirty helping out. Hopefully it will be a nice project for the two of you. He didn't look to thrilled in the first couple of pics. LOL. I would put a gold paint job on that and make a nice Rockford car.

JC455 · « **Reply #20 on:** May 07, 2018, 03:26:51 PM »

Quote from: ryeguy2006a on May 07, 2018, 01:03:36 PM

Wow, love this build! I would like to know more about that Z51 rear brake kit. I just picked up a complete set of Z51 rotors and calipers with brackets at a swap meet. I already swapped out the C5 rotors and calipers for the big Z51, but was looking to somehow adapt the rear Z51's to the rear LS1 brakes I currently have.

I haven't tried fitment with the LS F-car brakes, only the S10 stuff. I am using a standard rear caliper(2 lh sides) and standard abutment. The spacing is achieved in the spacer bracket.
Since you already have the parts, you might consider trying to put the Z51 rotor on, then see how close your caliper bracket is to aligning with the LS backing plate- might be surprised.. and end up pioneering a new hybrid

JC455 · « **Reply #21 on:** May 07, 2018, 03:28:00 PM »

Quote from: roadking77 on May 07, 2018, 01:24:29 PM

Looking forward to this one. I'm glad your son has gotten his hands dirty helping out. Hopefully it will be a nice project for the two of you. He didn't look to thrilled in the first couple of pics. LOL. I would put a gold paint job on that and make a nice Rockford car.

Yeah, he was being a grumpy 13 y/o! LOL

JC455 · « **Reply #22 on:** May 07, 2018, 03:33:20 PM »

Something to always consider- these are E/T acorn nuts. E/T is extended thread-- these give you an extra measure of safety!

Jack · « **Reply #23 on:** May 07, 2018, 07:26:28 PM »

Nice project, I like the special affects lol.

Question - how does the ET nut work, where does the ET go?

JC455 · « **Reply #24 on:** May 08, 2018, 09:13:20 AM »

Quote from: Jack on May 07, 2018, 07:26:28 PM

Nice project, I like the special affects lol.

Question - how does the ET nut work, where does the ET go?

They go down into the rim, below where the acorn section would normally wedge itself into.
If you were to place an E/T acorn into a lug nut hole on a loose rim, you'd see how it goes down much further into the rim (without bottom out and sticking past the back of the rim), thereby offering much more thread engagement to secure the rim to the stud.

MNBob · « **Reply #25 on:** May 08, 2018, 09:38:44 AM »

Quote

Many years ago, I was on NastyZ28.com and Pro-Touring.com and publicly commented on the similarity of the S10 and Corvette rear parking brake setup, and speculated that they could be used together as a hybrid. A gentleman who produces brake setups exchanged emails and PM's with me, and then he started marketing these:

Well, since I know what is involved in making it work, I just gathered my own parts to allow a staggered, C6 Z51 Corvette rear caliper disc brake setup. I just need to measure and cut some brackets to space the caliper upward from the S10 backing plate.

Whoa!!! I already have the Blazer rear disks. Are you telling me that all I need is the some brackets and maybe some shims and I can upgrade to the 13" Corvette rear disks? The drum in hat parking brake is the same size?

I probably wouldn't want to make my own brackets, but would just call him and purchase the brackets and anything else needed.

Good luck on your build, I look forward to seeing it. Nice choice of wheels (I have the 17's). You definitely will have great stopping power with that setup. Also, a great father and son project! The ET lug nuts are great; I used them with my previous factory wheels. I was not happy with the factory width of the stud engagement althoudh they say it is all you need.

JC455 · « **Reply #26 on:** May 08, 2018, 11:10:55 AM »

Quote from: MNBob on May 08, 2018, 09:38:44 AM

Quote
Many years ago, I was on NastyZ28.com and Pro-Touring.com and publicly commented on the similarity of the S10 and Corvette rear parking brake setup, and speculated that they could be used together as a hybrid. A gentleman who produces brake setups exchanged emails and PM's with me, and then he started marketing these:

Well, since I know what is involved in making it work, I just gathered my own parts to allow a staggered, C6 Z51 Corvette rear caliper disc brake setup. I just need to measure and cut some brackets to space the caliper upward from the S10 backing plate.

Whoa!!! I already have the Blazer rear disks. Are you telling me that all I need is the some brackets and maybe some shims and I can upgrade to the 13" Corvette rear disks? The drum in hat parking brake is the same size?

I probably wouldn't want to make my own brackets, but would just call him and purchase the brackets and anything else needed.

Good luck on your build, I look forward to seeing it. Nice choice of wheels (I have the 17's). You definitely will have great stopping power with that setup. Also, a great father and son project! The ET lug nuts are great; I used them with my previous factory wheels. I was not happy with the factory width of the stud engagement althoudh they say it is all you need.

Yes, sir!
I'll try to dig up my parking brake kit and take a pic of it in the C6 Z51 rear rotor.
You can 'almost' get away with a regular C5/C6 rear disc, but the spacing is a little too tight, that's why the C6 Z51 rotor is used.
By using the spacer bracket, a regular C5/C6 rear caliper/abutment can be used w/ the Z51 rotor, so no need to buy the Z51 abutment.

MNBob · « **Reply #27 on:** May 08, 2018, 12:15:07 PM »

I already have the big square spacers that fit over the axle tube (shown in your picture above at the bottom). I was just wondering if any shims were required from the extension brackets you are going to make and the caliper abutments. Maybe the top washers in the picture?

JC455 · « **Reply #28 on:** May 08, 2018, 01:08:24 PM »

Quote from: MNBob on May 08, 2018, 12:15:07 PM

I already have the big square spacers that fit over the axle tube (shown in your picture above at the bottom). I was just wondering if any shims were required from the extension brackets you are going to make and the caliper abutments. Maybe the top washers in the picture?

I don't think so- basically, the spacer/adapter plate is bolted to the S10 backing plate on the backing plate side, then the Corvette caliper bolts on to the backing plate on the rotor side- essentially creating a taller, wider mount for the caliper.
I think the washers you're referring to are for the caliper mounting bolts.
I'll know for sure once I get the plates made.
Q: Since you're running the same style of rim, how much clearance do you have at the wheel well lip? I currently have drums on the back, and I imagine the discs are going to space the rim outward a little bit, so I'm curious how you're doing in the rub department.
Thanks!

MNBob · « **Reply #29 on:** May 08, 2018, 02:25:51 PM »

Quote

This will look really good with some lowering springs in the rear.

You can also use lowering blocks to bring it down. I have the 1" blocks.

Thanks for all your responses. It looks like I will be upgrading my rear brakes as time permits. Might as well upgrade the fronts also with the Corvette 12.88" detachable rotors. I never liked rotor in hub anyway.

The rims I have are 17 x 8 with the same 4.5" backspacing as the originals. The rear tires are slightly larger than the originals at 28" (235 x 60 x 17). There is no issues with clearance or rubbing. I did have rubbing with the 15's when I had 255 x 70 x 15.

Here are a couple of photos:

Tire Side View

Tire Clearance Up View

JC455 · « **Reply #30 on:** May 09, 2018, 10:45:11 AM »

Thanks for the pics

I am running wider tires up front (245 45/18) and tires and rims in the rear (275 40/18 18x9.5), so that's where I may encounter some issues... we'll soon see

JC455 · « **Reply #31 on:** May 09, 2018, 10:49:11 AM »

More info on the S10/C6 Z51 hybrid rear brake setup- these are the parts I purchased:

This is the contents:

Here is the S10 e-brake shoe fitted inside the C6 Z51 rear rotor:

Here are two alternate sources for the rear shoe service kits, as the number I posted doesn't seem to be in stock anywhere:

MNBob · « **Reply #32 on:** May 09, 2018, 01:14:58 PM »

What I like about this upgrade (and the fronts) to C5/C6 hardware is you can get the parts anywhere and they are all off the shelf. I got a lot of my Blazer rear disk parts from Amazon!

The shoes I purchased at Amazon were the 179-2115 you listed. They are currently not available, although they suggest 179-2118 as an alternative. And then you have the 1792047 number so I am not sure what the differences are, if any. Sometimes there are just superseded numbers.

JC455 · « **Reply #33 on:** July 05, 2018, 07:31:30 AM »

A little sneak peek of what's to come...

JC455 · « **Reply #34 on:** July 05, 2018, 07:35:57 AM »

... and just so people understand who is building these for Summit Racing:

Jack · « **Reply #35 on:** July 08, 2018, 09:06:28 AM »

You got me interested in converting to EFI but will see how it works out for you first LOL.

roadking77 · « **Reply #36 on:** July 09, 2018, 07:21:21 AM »

I wanted to go efi when I built my motor just because... My builder talked me out of it. Also curious to see how you like it.

4wheeling79 · « **Reply #37 on:** July 09, 2018, 01:57:41 PM »

Looking good I will be following along what plans do you have for motor and trans?

JC455 · « **Reply #38 on:** July 17, 2018, 01:45:30 PM »

Plans: Right now, it's a stock 400/TH400 setup. I'll put a little bit of cam into it, possibly some Rhoads lifters to keep it more docile, a light stall torque convertor, some 6X-4 heads to replace the 4X heads that're on it (I'm not a fan of the 4X castings- every set I've had ended up with cracks in them... maybe it's just my bad luck, I don't know, but I'm not going to bother sinking money into them), some steel roller tip rocker arms, and either a Holley Street Dominator or a Tomahawk's version of a single plane intake.
I've been saving again for a Tanks Inc. fuel tank, mounting straps, fuel pump, floatless sending unit, AN fittings and adapters, Earl's fuel hose... etc. LOL

Nexus · « **Reply #39 on:** July 18, 2018, 03:09:44 AM »

Just came across your build...very cool...I like the brake upgrade idea...makes me want to do it to mine...if and when I get to that stage...need a garage first

keep the posts coming...along with pictures of course!!

« **Reply #39 on:** July 18, 2018, 03:09:44 AM »

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Author Topic: 1974 Formula 400 build (Read 1621 times)